> but after this you can switch to your favorite build system.

You can build the boost_python runtime with any build system you like. E.g. I have been using scons for years. You just have to get the compile & link commands right.
In the past there was a way to get bjam (version 1) show the commands it was issuing, I think it was -d2. I guess something similar if not the same should also work with the current bjam.
Ralf